Question

How to draw a box with 4 lines using SDL3 in Win32 C++

Answer 1

#include <SDL3/SDL.h>

#if _WIN32 // PLATFORM_WINDOWS 

#define WIN32_LEAN_AND_MEAN // Exclude rarely-used stuff from Windows headers
#include <windows.h>

int APIENTRY wWinMain(_In_ HINSTANCE hInstance,
    _In_opt_ HINSTANCE hPrevInstance,
    _In_ LPWSTR lpCmdLine,
    _In_ int nCmdShow) {

    if (!SDL_Init(SDL_INIT_VIDEO)) {
        //SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't initialize SDL: %s", SDL_GetError());
        MessageBoxA(0, SDL_GetError(), "Couldn't initialize SDL", MB_OK);
        return 3;
    }

    SDL_Window* window;
    SDL_Renderer* renderer;
    if (!SDL_CreateWindowAndRenderer("SDL3 Draw a box with 4 lines", 640, 480, SDL_WINDOW_RESIZABLE, &window, &renderer)) {
        //SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't create window and renderer: %s", SDL_GetError());
        MessageBoxA(0, SDL_GetError(), "Couldn't create window and renderer", MB_OK);
        return 3;
    }

    SDL_Event event;

    while (1) {
        SDL_PollEvent(&event);
        if (event.type == SDL_EVENT_QUIT) {
            break;
        }

        // set backround color
        SDL_SetRenderDrawColor(renderer, 33, 33, 33, SDL_ALPHA_OPAQUE); // dark gray
        SDL_RenderClear(renderer); // start with a blank dark gray canvas

        // set lines colors
        SDL_SetRenderDrawColor(renderer, 38, 203, 55, SDL_ALPHA_OPAQUE);

        // bool SDLCALL SDL_RenderLine(SDL_Renderer *renderer, float x1, float y1, float x2, float y2);

        // draw the box with lines, one at a time
        SDL_RenderLine(renderer, 240, 156, 400, 156); // top line -
        SDL_RenderLine(renderer, 240, 350, 400, 350); // bottom line -
        SDL_RenderLine(renderer, 400, 156, 400, 350); // right line |
        SDL_RenderLine(renderer, 240, 156, 240, 350); // left line |
        
        SDL_RenderPresent(renderer); // put all on the screen
    }

    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);

    SDL_Quit();

    return 0;
}

#endif

 

70+ SQL courses for beginners and professionals